Particles disappear when no physics set
Hair particles are in fact trajectories of regular particles ; the regular particle need to have a motion, so it needs physics. Of course this is not a real motion, as it don't vary in time, but a path, a trajectory.

To reduce render time, you can turn off Hair Dynamics, which is the motion applied to every hair particle. It is off by default.

It's kinda weird to use hair particles to render actual objects. A regular particle system would work fine and is much easier to configure.